The present invention relates to electric feedthrough systems applied to transmit electrical power from an above ground source to equipment having a subterranean location. Its essential features insure the integrity of such a system, even under the most adverse conditions, and to a degree not heretofore achieved.
In the embodiment herein illustrated the invention is particularly concerned with that portion of a cable system which is projected through, connected to and depends from the head of a well to form a connection between an above ground cable connected to a source of electrical power and an underground cable connected to a pump which is submerged within the depths of the well. As is particularly well known in the oil industry, the maintenance of power to such a pump is critical and at the same time made difficult by reasons of the extreme in pressures and temperatures and the character and nature of the well fluids to which the portion of the electric feedthrough system at the wellhead is subjected.
That many problems have resulted from such circumstances has been frequently exhibited in the prior art apparatus applied for the same purpose. This is well known. These problems have stemmed from many factors not the least of which has been the design characteristics of prior art apparatus which in many cases include the requirement for complete bonding of insulators and dielectrics thereof to one another and to the conductors which they peripherally encase as well as to the shell or housing by which they themselves are encased. Such requirement is most difficult to satisfy. Apart from this, it is often difficult to introduce a dielectric material in such apparatus in a manner to render it void free. As will be self apparent, the existence of voids in a dielectric material makes such material highly susceptible to a structural breakdown under the exceedingly high differential of pressures and/or voltage to which it may be subjected in a well environment, particularly in the vicinity of a wellhead. Where bonding is not perfect and dielectrics are not void free, as will be obvious, the pressure and temperature conditions within a well will make that portion of the electric feedthrough apparatus with which we are presently concerned, at the vicinity of a wellhead, subject to infiltration by and seepage therein and therethrough of well fluids with many undesirable results, one or more of which will follow. Such undesirable results include short circuiting and interruption of the function of the pump being powered. However, this is not the worst. It can also produce an escape through the electric feedthrough system and the portion of the wellhead to which it mounts of fluids which are lethal and are contaminating to the atmosphere. Also arcing can result therefrom producing the danger of catastrophic consequences in the environment of and in the above ground area of the well in which there is a breakdown of the electric feedthrough system, particularly where the well is an oil and/or gas well and any fire resulting may spread throughout the well field. The problems stated are compounded by the usual practice of having a plug in joint in the electrical feedthrough systems for its connection to the lower cable which is spliced to that portion of the cable system originally connected to the pumping equipment to be powered. The plug in joint is located in the region where there may be aggressive, deadly fluids under pressure. This joint has been the "weakest link" in current designs.
The improvements of the present invention substantially obviate the above mentioned problems and enable a much greater degree of safety in the operation of electrically powered equipment in the environment of fluids of a highly volatile or dangerous character and subject to conditions of high pressures and temperatures which are variable in character and wherein portions of the electrical feedthrough systems supplying the necessary power are by reason of the location thereof subject to substantial differentials of temperature and pressure.
The inventor believes the general and current state of the art pertinent to the area of the present invention is represented by the disclosure of the following U.S. Letters Patent, namely: No. 4,154,302, May 15, 1979, Edward T. Cugini; No. 4,041,240, Aug. 9, 1977, Alexander D. Sipowicz; No. 3,437,149, Apr. 8, 1969, E. T. Cugini et al.
The inventor is not aware, however, of any prior art which is specifically pertinent to the improvements of the present invention as herein set forth and specifically claimed.